1. Technical Field
The present invention relates to an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus.
2. Related Art
Generally, an electrophotographic image forming apparatus has the following structure and processes. Specifically, the surface of an electrophotographic photoreceptor is charged by a charging means to desired polarity and potential, and the charged surface of the electrophotographic photoreceptor is selectively removed of charge by subjecting to image-wise exposure to form an electrostatic latent image. The latent image is then developed into a toner image by attaching a toner to the electrostatic latent image by a developing means, and the toner image is transferred to an image-receiving medium by a transfer means, then the image-receiving medium is discharged as an image formed material.
Electrophotographic photoreceptors are currently been widely used in the field of copying machines, laser beam printers and other apparatus due to advantages of high speed and high printing quality. As electrophotographic photoreceptors used in image forming apparatus, organic photoreceptors using organic photoconductive materials are mainly used which are superior in cost efficiency, manufacturability and disposability, compared to conventionally used electrophotographic photoreceptors using inorganic photoconductive materials such as selenium, selenium-tellurium alloy, selenium-arsenic alloy and cadmium sulfide.
As a charging method, a corona charging method utilizing a corona charging device has been conventionally used. However, a contact charging method having advantages such as low ozone production and low electricity consumption has recently been put into practical used and is widely used. In the contact charging method, the surface of a photoreceptor is charged by bringing a conductive member as a charging member into contact with, or in close proximity to, the surface of the photoreceptor, and applying a voltage to the charging member. There are two methods of applying a voltage to the charging member: a direct current method in which only a direct current voltage is applied, and an alternating current superimposition method in which a direct current voltage superimposed by an alternating current voltage is applied.